Introduction to aspirin – an essential medicine:
Aspirin is a weak organic acid – acetylsalicylic acid. It is obtained naturally from the Willow bark which contains Salicin. It can also be produced synthetically.
It is mainly a non-opioid analgesic and non steroidal anti-inflammatory drug and is the initial choice of drug in the treatment of articular (arthritis) and musculoskeletal disorders.
Chief pharmacological actions of aspirin:
1. Anti-inflammatory action (Peripheral nervous system effect)
2. Analgesic action (pain-killer) (Both Central and Peripheral nervous system effect)
3. Anti-pyretic action (reduces fever) (Both Central and Peripheral nervous system effect)
4. Anti-platelet action (prevents platelet aggregation) ( Peripheral nervous system effect)
Other effects of aspirin:
1. Stimulates respiratory center so increases the repiration rate
2. Uncoupling of oxidative phosphorylation
1. Mild reversible hepatic damage
2. Increase SGPT and SGOT level
3. Reye’s syndrome
1. Increase steroid synthesis
2. Thyroid suppression by decreasing iodine uptake
3. Prolongs the labor period
Large dose (>5g/day) cause inhibition of prothrombin synthesis in the liver.
1. Gastric irritation
Bleeding leading to iron deficiency anaemia
2. Nausea and vomiting by stimulation of chemoreceptor trigger zone (CTZ)
3. Reduces the cytoprotective role of PG PG E2 and PG I2 ie decreases mucous production and increases the hydrochloric acid secretion
Decreases the renal blood flow leading to renal salt and water retention leading to renal damage.